Recently, electric powered vehicles including electric vehicles, hybrid vehicles and fuel cell vehicles have been developed and come to be practically used as environmentally friendly vehicles. In such an electric powered vehicle, a traction motor and a power storage device for accumulating electric power for driving the traction motor are mounted. In a power source system for such an electric powered vehicle, generally, a switch represented by an electromagnetic relay is provided to control conduction and cut-off of power input/output path for the power storage device.
By way of example, Japanese Patent Laying-Open 2008-187884 (PTL 1) describes an arrangement of a power source system for a vehicle having a plurality of power storage devices, in which system relays are arranged corresponding to the plurality of power storage devices respectively. Further, PTL 1 describes system relay control of the power source system, which allows continuous power supply to a load device even when part of the power storage devices are electrically disconnected from the load device as necessary.